Locked comment text

Hi,

I've recently come across a problem where I am unable to add comment texts in any pdf I open (even in ones that I previously was able to).  When I look at the properties for the text comment it shows this which I am unable to click.

I tried looking at other forums for answers. I deleted acrobat a few times, which didn't work and I looked back at all my old files to see if I had set my lock as default for anything else. I did find one text box which was locked and I was able to unlock that one (which fixed a locked text box issue I also had previously) but it did not change the text comment. Any help on this matter would be much appreciated; I have the most up to date version of Acrobat Reader and use a Mac.